Continuous method of chromium plating metallic wires or strips



March 3, 1931.

B. v. M BRIDE 1,794,973

CONTINUOUS METHOD OF' GHROMIUM PLATING METALLIC WIRES OR STRIPS Filed March 27, 1928 2 Sheets-Sheet 1 INVENTOR Byron l/M Br-z'de.

ATTORNEY March 3, 1931. B. v. M BRlDE 1,794,973

CONTINUOUS METHOD OF CHROMIUM PLATING METALLIC WIRES OR STRIPS Filed Marchi27, 1928 2 Sheets-Sheet 2 Fig. 3.

INVENTOR B yran 1/ M Brz'da PITTORNEY Patented Mar; 3, 1931 UNITED STATES PATENT OFFICE BYRON V. MOIBBIDE, OF IRWIN, PENNSYLVANIA, ABBIGNOB TO WESTINGHOUSE ELEC- TBIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA CONTINUOUS METHOD OF CHROIIUI PLATING EETALLIC WIRES OR STRIPS Application filed larch 27, 1828. Serial No. 264,984.

My invention relates to a continuous process of electrolytically plating metalliowires or ribbons with protective layers or coatings of another metal, and particularly to the proc- 5 ess of coating wires or ribbons with metallic chromium.

An object of my invention is to provide a method of electrolytically coating wires or ribbons with protective layers of another metal, and particularly chromium, in such a manner that the process will be continuous and all parts of the wires or ribbons will be uniformly coated.

Another object of my invention is to provide an apparatus for uniformly and continuously electroplating metallic wires or strips with chromium, or other metal, which consists, essentially in providing a plurality A of anodes and arranging them in such manner that, as the metallic ribbon or wire is drawn through the bath, all parts of its will be at a substantially equal distance from the anodes, and the entire surface of the wire or strip will, accordingly, receive a uniform coating of the electrodeposited metal.

A still further object of m invention is to provide a method for electro ytically coating wires or ribbons with metallic chromium or other metal in such manner that, during partial travel of the wire through the plating solution, it will be insulated from the voltaic action of the bath.

In electroplating wires or ribbons with metals, and particularly chromium, consider able difiiculty has been experienced in securing uniform coatings of-the metal on the entire surfaces of the wires or ribbons. When it was desired to coat a metallic strip or ribbon, for example, the side in closest proximity to the anode was exposed to the direct voltaio action of the bath and would be plated more heavily than the opposite side, resulting in a ribbon having an irregular coating of the electrodeposited metal.

In my improved process, I have provided an additional anode and have arranged the wire or ribbon that serves as the cathode in such a manner that, while it is being drawn vertically through thebath, all portions are at substantially equal distances from the anode and are exposed directly to the voltaic action of the bath, but, during the horizontal travel of the wire through the bath, when all portions of the wire or ribbon are not at substantially equal distances from the anode and are not exposed directly to the voltaic action of the bath, the wire or ribbon is effectively insulated from the plating action of the bath.

As the wire or ribbon is drawn through the bath, I am, therefore, able to secure an electrodeposited coating which is uniform in all respects and, while my process may be employed in electrodepositing metals of all kinds, it is especially adapted to the electrodeposition of chromium which is particularly sensitive to slight variations in the compositon of the bath and the location of the anodes. My invention will be better understood when taken in conjunction with the accompanying drawing, in which,

Figure 1 is a cross-sectional view of the plating apparatus, taken on the line II of Fig. 2, showing means for drawing the wire or ribbon through the bath;

Fig. 2 is a plan view of the apparatus shown in Fig. 1, the motor for drawing the wire or ribbon through the bath being omitted;

Fig. 3 is a side view of the central metallic anode; and

Fig. 4 is a cross-sectional view of a modification of the apparatus shown in Fig. 1.

Referring to Figs. 1, 2 and 3 of the drawings, the numeral 1 designates a wooden tank provided with a lead lining 2 which has an outwardly extending flange 3 at its upper portion extending over the upper edge of the wooden tank. The longitudinal sides of the lead lining are bent downwardly at their central ortion to provide an offset portion 4 which ts into grooves provided in the central portion of the longitudinal sides of the wooden tank. The offset portion of the lead lining 3 provides a bearing for a rod 5, to

which an additional anode 6 may be secured motor 19.

rectangular portions and 11, respectively, and a reinforcing member 12, is placed in the plating solution and rests upon the glass panel 8.

Appropriate supply and receiving reels 13 and 14, respectively, are rotatably mounted upon the upper rectangular portion 10 and, during the plating operation, the ribbon or strip is drawn slowly through the bath, be-

I ing guided in its course by two pairs of rollers15-l5 and 16-16 mounted on reinforcing member 12 and the lower rectangular portion 11, respectively.

An additional glass. panel 17 rests upon the lower rectangular portion of the frame above the rollers 16'16, and in conjunction with the lower horizontally extending glass.

panel 8 and two vertically extending glass panels 18, serves to insulate the wire or ribbon from the voltaic action of the bath while it is passing horizontally through the plating solution.

, passage of the ribbon or strip through the solution, however, the favorable conditions above specified do not prevail, and, in order to obtain a uniform coating, the ribbon or strip is insulated from the plating action of the bath during its horizontal movement.

Fig. 2 of the drawing is a modified form of the invention, being particularly adapted for the coating of metallic wires with chromium. The apparatus utilized is essentially the same as that described in the embodiment employed for the plating of ribbons or strips, with the exception that, instead of utilizing a leadlined vessel, cylindrical lead anodes 21 are employed which fit into apertures provided in glass panel 17 The corresponding parts have accordingly been designated by the same numeralsas in Figs. 1, 2 and 3.

As the wire 23 is drawn vertically through the bath, all portions will beequidistant from the anodes and will be uniformly plated.

During the horizontal travel of the 'wire through the bath, however, it will be insulated from the plating action of the bath. The cylindrical tubes 21 are provided with flanges 22 which rest upon glass panel 17 and are connected together and braced at their upper portion by means of a conducting material 24.

Any suitable plating solution may be employed but I prefer to utilize a bath composed of about 33.3 ounces of chromium trioxide and 1 ounce of chromic sulphate to each gallon of water. The current density at the cathode is maintained at from about 1 to 1 amperies per square inch, and the temperature of the bath at from 45 to 50 C. It will be understood, however, that the composition and temperature of the bath and-the cathode density may be varied to a reasonable extent without materially affecting the efficiency of the process. The rate at which the Wire or ribbon is drawn through. the bath will also vary in accordance with the thickness of the coating, desired, although, in order to produce an efficient coating, it is usually desirable to draw the wire or ribbon through the bath very slowly, and, if desired, the motor may be equipped with a suitable speed-reducing mechanism for this purpose.

While I have described a preferred embodiment of my invention,-it will be understood that various modifications may be made therein without departing from the spirit of my invention. For example, although I have specified that my process is particularly adapted for chromium plating, other metals may be successfully plated by my improved process. It will also be understood that the wire or ribbon may be utilized in either modification shown and, if desired, it'may be thoroughly cleaned and polished before passing it through the bath.

Other modifications of my invention will become apparent to those skilled in theart.

I desire, therefore, that only such limitations shall be placed upon my invention as are imposed by the prior art and in the appended claims.

I claim as my invention.

1. In the process of electroplating a wire or ribbon with a protective layerof chromium, the step which comprises continuously drawing the wire or ribbon through a plating bath containing chromic acid and chromic sulphate and provided with a lead anode in such.

manner that, during the vertical travel of the wire or ribbon through the bath, all portions of it will be substantially equidistant from the anode and exposed to the direct voltaic action of the bath but during horizontal travel, when all portions are not equi distant from the anode, the wire or ribbon will be almost completely insulated from the voltaic action of the bath.

2. A continuous process of electrodepositing a protective layer of chromium upon a metallic wire or ribbon which comprises drawing the wire or ribbon downwardly through a suitable chromium-plating solution in such manner that all portions are substantially equidistant from the anode and exposed directly to the voltaic action of the bath, passing it horizontally through the plating solution, while insulating it almost completely from the voltaic action of the bath, and then drawing it upwardl throu h the solution in such manner that uring e upward travel, all portions are again substantially equidistant from the anode, and

said lining substantially midway between the I ends of saidlining and means for so movin the metallic wire or ribbon through said bat that, during vertical travel all portions of it will be substantially equidistant between said end portions and said central anode.

4. An apparatus for continuously electroplating metallic wire or ribbon, comprising a metallic enclosure for a suitable platin bath which serves as an anode, an additiona anode dividing said enclosure into substantially two equal portions, means for drawing said metallic wire or ribbon through said bath so that all portions of it will be exposed to the voltaic action of the bath during its vertical travel and meansfor insulating it from the voltaic action of the bath during its horizontal travel.

5. An apparatus for continuously electroplating a wire or ribbon comprising an enclosure for a suitable plating bath and a plurality of anodes, means for drawing the wire or ribbon partially in a vertical and partial] in a hroizontal direction through said bat so that, during the vertical travel through the bath, all portions of it will be exposed to the voltaic action of the bath and means located on all sides of the wire or ribbon for insulating it from the action of the bath during its horizontal travel.

7 6. An apparatus for continuously electroplating metallic wire or ribbon comprising a suitable enclosure containing a plating bath, means for'drawing a wire or strip in different directions through the bath, anodes spaced at a substantially equal distance from all portions of the wire or strip during artial travel of the same through-the bat in one direction, and means located on all sides of the wire or ribbon for insulating it from the lating action of the bath when the arm es are not at a substantially equal distance from the wire or stri p In testimony whereof, f have hereunto subscribed my name this 22nd day of March,

BYRON V. MCBRIDE. 

